Abstract: A storage unit including redundant storage includes: a primary storage unit and a journal for managing execution of incomplete writing of data for at least two overlapping data segments, a reference table for tracking incomplete writes of data; and includes instructions for managing data by: monitoring writes of data to identify incomplete writes of data sharing at least one designated storage location of a primary media; reading the associated writes of data into the table; sequencing the associated writes of data; writing data in sequence order to each designated storage location of the primary media and providing the data in sequence order to secondary media with a sequence number; and at least one secondary storage unit including a duplicate record of data comprised within the primary media, each secondary storage unit equipped for ensuring recent data is not overwritten with prior data by controlling writes according to the sequence number.

Abstract: A storage controller, cooperable with host computer apparatus, and a plurality of controlled storage apparatus, comprises a host write component operable to write a data object to a source data image at one of the plurality of controlled storage apparatus; a first copy component responsive to a first metadata state and operable to control copying of the data object to a first target data image at one of the plurality of controlled storage apparatus; a second copy component responsive to a second metadata state and operable to perform one of: controlling copying of the data object to a second target data image at one of the plurality of controlled storage apparatus; and causing the first copy component to perform copying of the second target data image to the first target data image.

Abstract: Methods and systems for memory management. A method for memory management includes: maintaining a reference count for at least one first process associated with a portion of memory; maintaining a shared reference count for at least one second process associated with the portion of memory; and freeing the portion of memory when the shared reference count is decremented to zero.

Abstract: A storage control apparatus cooperable with a plurality of controlled storage apparatus arranged in a cascade of point-in-time copy relationship. The apparatus includes: a rate control component operable to set a desired rate for making clean a first target one of the plurality of controlled storage apparatus; a comparator component responsive to a signal from the rate control component to request and receive metadata from the plurality of controlled storage apparatus and to identify discrepant metadata; and a copy initiator, responsive to the comparator component to identify discrepant metadata and to initiate a copy operation from a first target one of the plurality of controlled storage apparatus to a second target one of the controlled storage apparatus.

Abstract: A storage network control apparatus is operable to present virtualized storage to a host system and includes a monitoring component, an analysis component, a detection component, and a migration component. The monitoring component is for monitoring input/output (I/O) activity for virtual storage logical units over time. The analysis component is for identifying a repeating instance of peak I/O activity for a virtual storage logical unit over time and for generating a predictive signature therefrom. The detecting component is for identifying an instance of such a predictive signature. The migration component is responsive to the detecting component, and is for migrating data mapped by the virtual storage logical unit across additional real storage units to improve the I/O performance of the virtual storage logical unit prior to a recurrence of the repeating instance of peak I/O activity. A corresponding logic arrangement may be incorporated in hardware, software or a combination thereof.

Abstract: A method, storage system, and machine-readable medium for resynchronizing data stored among a first storage element and a second storage element of a remote copy pair of storage elements is disclosed. According to one embodiment, a method is provided which includes detecting a reestablishment of a remote copy relationship between the first and second storage elements and performing a resynchronization operation in response to this detection. Performing the resynchronization operation comprises transmitting data of a second change record associated with the second storage element to the first storage element, combining the second change record with a first change record associated with the first storage element, identifying a data segment of the second storage element utilizing the combined change record, and overwriting data of the first storage element with data of the identified data segment.

Abstract: A method, storage system, and machine-readable medium for resynchronizing data stored among a first storage element and a second storage element of a remote copy pair of storage elements is disclosed. According to one embodiment, a method is provided which includes detecting a reestablishment of a remote copy relationship between the first and second storage elements and performing a resynchronization operation in response to this detection. Performing the resynchronization operation comprises transmitting data of a second change record associated with the second storage element to the first storage element, combining the second change record with a first change record associated with the first storage element, identifying a data segment of the second storage element utilizing the combined change record, and overwriting data of the first storage element with data of the identified data segment.

Abstract: An apparatus is disclosed in which a storage controller cooperable with a host and a plurality of controlled storage is provided to localize an impact of a failure to a target disk in an affected segment. The storage controller includes a host write component to write a data object to a source image storage; a first copy component responsive to a first metadata state to control copying of the data object to a first target storage; a second copy component responsive to a second metadata state to perform either: copying the data object to a second target or causing the first copy component to copy the second target to the first target; and a third copy component to control cascaded copying of the data object to a third target storage. Either the second or the third copy component controls cascaded copying of a delimited data image subsequence responsive to a metadata state indicating currency of a data grain in either the second or the third target.

Abstract: A storage controller, cooperable with host computer apparatus, and a plurality of controlled storage apparatus, comprises a host write component operable to write a data object to a source data image at one of the plurality of controlled storage apparatus; a first copy component responsive to a first metadata state and operable to control copying of the data object to a first target data image at one of the plurality of controlled storage apparatus; a second copy component responsive to a second metadata state and operable to perform one of: controlling copying of the data object to a second target data image at one of the plurality of controlled storage apparatus; and causing the first copy component to perform copying of the second target data image to the first target data image.

Abstract: A storage network control apparatus is operable to present virtualized storage to a host system and includes a monitoring component, an analysis component, a detection component, and a migration component. The monitoring component is for monitoring input/output (I/O) activity for virtual storage logical units over time. The analysis component is for identifying a repeating instance of peak I/O activity for a virtual storage logical unit over time and for generating a predictive signature therefrom. The detecting component is for identifying an instance of such a predictive signature. The migration component is responsive to the detecting component, and is for migrating data mapped by the virtual storage logical unit across additional real storage units to improve the I/O performance of the virtual storage logical unit prior to a recurrence of the repeating instance of peak I/O activity.

Abstract: A storage controller, cooperable with host computer apparatus, and a plurality of controlled storage apparatus, comprises a host write component operable to write a data object to a source data image at one of the plurality of controlled storage apparatus; a first copy component responsive to a first metadata state and operable to control copying of the data object to a first target data image at one of the plurality of controlled storage apparatus; a second copy component responsive to a second metadata state and operable to perform one of: controlling copying of the data object to a second target data image at one of the plurality of controlled storage apparatus; and causing the first copy component to perform copying of the second target data image to the first target data image.

Abstract: A method and apparatus is disclosed in which a storage controller cooperable with a host and a plurality of controlled storage is provided to localize an impact of a failure to a target disk in an affected segment. The storage controller includes a host write component to write a data object to a source image storage; a first copy component responsive to a first metadata state to control copying of the data object to a first target storage; a second copy component responsive to a second metadata state to perform either: copying the data object to a second target or causing the first copy component to copy the second target to the first target; and a third copy component to control cascaded copying of the data object to a third target storage. Either the second or the third copy component controls cascaded copying of a delimited data image subsequence responsive to a metadata state indicating currency of a data grain in either the second or the third target.

Abstract: A host data processing system includes a data storage system having a cache memory and a back end storage. In response to a detection of an event failure during an input/output (I/O) request from the host data processing system to the data storage system, the data associated with the I/O request is forwarded to the back end storage data, and a copy of the data associated with the I/O request is sent to the cache memory. A determination is made as to whether or not there is an acknowledgement from the back end storage regarding the receipt of the data associated with the I/O request. If there is an acknowledgement from the back end storage regarding the receipt of the data associated with the I/O request, the data associated with the I/O request is flushed from the cache memory, and the received acknowledgement is routed to the host data processing system.